The present invention relates to a method of identifying a frame number of a picture frame of a photographic film, and more particularly to a method of identifying a frame number of a photographic film placed in a film framing mask, which method is used in a photographic printer, a negative film inspection apparatus, a numbering apparatus for printing frame numbers on prints or the like.
Disk films now available have a circular arrangement of exposable frames at regular angular intervals or spacings, each exposable frame being attached with a decimal number and a binary bar code both of which are latent images and represent a serial frame number. In a disk film printing system, the binary bar code is read with bar code sensor or bar code reader to print a decimal number representative of the serial frame number of each exposed frame of the disk film on the back surface of a print. Moreover, to provide extra prints of an exposed frame, the only operation required for the disk film printing system is to enter into the system data representing the serial frame number of the picture frame to be printed and the number of extra prints to be made from the picture frame. The disk film printing system reads binary codes based on the entered data to identify the serial frame number of the picture frame and then automatically places the picture frame having the specified serial frame number at a printing station. The disk film printing system, thereafter, automatically provides as many prints as requested.
Since the positions of respective exposed frames of a disk film are specifically fixed, the exposed frames and their frame numbers completely coincide with each other. However, a roll of photographic film. e.g., a 35 mm. size negative film, may not have a positive position when loaded in a camera, and exposed frames are often out of registry from correspondingly predetermined exposable frame positions. Consequently, the frame numbers printed on the film do not have one-to-one correspondence to the images, leading to many inconveniences. For instance, if extra prints of a picture frame are requested, a print made at the time the negative film is developed is visually compared with the negative film to identify the picture frame to be reprinted by its frame number.
There are known apparatus for easily identifying the frame number of a picture frame from which a print has been made. Such apparatus prints the frame number of a picture frame on the print at the time of first printing. For example, according to the apparatus disclosed in Japanese Unexamined Patent Publication No. 56-128,933, a mark is recorded on the center line of the first picture frame of a negative film and, thereafter, the frame number of each picture frame at the printing station is specified, based on the length the negative film has advanced after detection of the mark. The specified frame number is then printed by a number printer either on the peripheral margin of a print of the picture frame or on the back surface of the print. Another apparatus is disclosed in Japanese Unexamined Patent Publication No. 52-111,718. In this apparatus, if extra prints of a picture frame are requested, the frame number of the picture frame to be printed is read by an optical character reader, such as an image sensor, to identify the requested picture frame and to place the picture frame having the identified frame number in position in the film framing mask at the printing station in order to make as many prints as requested.
A problem associated with the above described apparatus is the necessity of recording a start mark or of providing a complicated optical character reader. This problem may be solved by way of providing latent image bar codes indicating the frame numbers optically printed during manufacturing of a film aside the respective exposable frames of the negative film in a manner similar to that used in manufacturing the above noted disk films. The bar code can be read with an optical sensor disposed on the passage of the negative film to identify the frame number of a picture frame positioned in the film framing mask at the printing station.
Although the provision of bar codes makes it easy to read frame numbers, it is however, still hard to form an image at each exposable frame in proper registry with the bar code.